From: Robert Klemme <bob.news@...>
Date: 2005-09-06T17:26:27+09:00
Subject: Re: [Q] how to do insertion and smooth traversal simultaneously on array

Kroeger Simon (ext) wrote:
> as Robert said:
> -----------------------------------------------------------------
> a = [ 0, 1, 2, 3, 4, 5 ]
> actions = []
> a.each_with_index do |x, i|
>   puts "[#{i}] : #{x}"
>   if i % 2 == 0  # even index ?
>     actions << [a, :insert, [i, ':-)']]
>   end
> end
> # do it!
> actions.reverse.each{|action| action[0].send(action[1], *action[2])}
> puts a.size
> ------------------------------------------------------------------

You can slightly simplify this as

a = [ 0, 1, 2, 3, 4, 5 ]
actions = []
a.each_with_index do |x, i|
  puts "[#{i}] : #{x}"
  if i % 2 == 0  # even index ?
    actions << [a, [:insert, i, ':-)']]
  end
end
# do it!
actions.reverse.each{|obj, args| obj.send(*args)}
puts a.size, "", a

Although I like the idea to use #send in this case a simpler solution
would be sufficient:

a = [ 0, 1, 2, 3, 4, 5 ]
actions = []
a.each_with_index do |x, i|
  puts "[#{i}] : #{x}"
  if i % 2 == 0  # even index ?
    actions << [i, ':-)']
  end
end
# do it!
actions.reverse.each{|idx, val| a.insert(idx, val)}
puts a.size, "", a

Kind regards

    robert